The Obama White House tried to rush federal reviewers for a decision on a nearly half-billion-dollar loan to the solar-panel manufacturer Solyndra so Vice President Biden could announce the approval at a September 2009 groundbreaking for the company’s factory, newly obtained e-mails show.

The Silicon Valley company, a centerpiece in President Obama’s initiative to develop clean energy technologies, had been tentatively approved for the loan by the Energy Department but was awaiting a final financial review by the Office of Management and Budget.

The August 2009 e-mails, released to The Washington Post, show White House officials repeatedly asking OMB reviewers when they would be able to decide on the federal loan and noting a looming press event at which they planned to announce the deal. In response, OMB officials expressed concern that they were being rushed to approve the company’s project without adequate time to assess the risk to taxpayers, according to information provided by Republican congressional investigators.

Solyndra collapsed two weeks ago, leaving taxpayers liable for the $535 million loan.

One e-mail from an OMB official referred to “the time pressure we are under to sign-off on Solyndra.” Another complained, “There isn’t time to negotiate.”

“We have ended up with a situation of having to do rushed approvals on a couple of occasions (and we are worried about Solyndra at the end of the week),” one official wrote. That Aug. 31, 2009, message, written by a senior OMB staffer and sent to Terrell P. McSweeny, Biden’s domestic policy adviser, concluded, “We would prefer to have sufficient time to do our due diligence reviews.”